Method of making hub structures



June 19, 1945.

A. G. FORSYTH 2,378,842

METHOD OF MAKING HUB STRUCTURES Original Filed Nov. 3, 1942 3 Sheets-Sheet l MRQW Mama;

A.' G. FORSYTH METHOD'OF MAKING HUB STRUCTURES Original Filed Nov. 3, 1942 June 19, 1945.

June 19,- 1945. A. G: FORSYTH 2,378,842

METHOD OF MAKINQ HUB STRUCTURES Original Filed Nov. 3, 1942 5 Sheets-Sheet s K a 56 v a6 Patented June 19, 1945 NITE STATES \PATE M ndate MAKING HUB STRUCTURES Archibald Graham Forsyth, C heam, Engiandyassi'gnor to The Fairey Aviation Company, Lirnited, Hayes; England Original application November 3, 1942, Serial No.

r 464,369. Divided and this application Decem- J'Ihis invention relates to aprop eller hub; More particularly theinventionrelates to amethod of constructing a propeller hub for variable pitch propellers" Thlsapplicationis a division of my copending application Serial No.: 464,369; filed November 3, 1942.

Primarily" because of spacerequirements and v theicomplexitypof the mechanism required for changing the;pitch of variable pitch propeller blades, the hub-structures heretofore employed a'great number ofmachining operations and con-l sequently their manufacture, particularly in war j time, has not been i as rapid as is desired. It;is a; principal objector the present invention to avoid thesedrawbacks. i

'I he invention-hass es another object theprcvisionro f amethodof makinga simply designed hub for variable pitch propellers'which hub is comprised primarily 'of standard tubular pieces and-which witha few machining andbrazingor 10 have beemcompli'cated in nature and difiicult of n l manufacture. In: particular they have required;

Figure: 8 is a sectional view taken on the line Figure Sis a section tahenon the line 9-39 of 1 Figure 7;

tion employed as a part of the hub construe;

Figure 10 is a sectional View of a tubular section;

an additional machining operation has been made; n

Figure 12 is a horizontal section oftheghub construction after partial assembly;

weldingloperations can readilybe assembled in" final form; In accordance with the invention,

the construction is so designed astoenable its use:in;arrangementsembodying oneor more sets of variable pitch. propellers.

Anotherlobject of the invention resides in an improved method of constructing ahub unit for variablepitch propellers.

further object ofthe inv'entionresides in a method of making a hub structure which requii 'es" less material than heretoforefnecessary.n Consequently this effectsa great saving ofcritical materials. 1

and other bjects or the lamest will eeomampre apparentpin the following descrip tifiri 'antl claims when read in conjunction with the accompanying r g n l Figure 1 is a side elevation-of a hubcon strum' tionl embodying the invention; jflFigure-zisa frbntview;

rigure a' is an-enlargeddetail'view taken 11' the Figure iris a vertical section taken on-the line-P-Wof Figure 5 through the principaltubular member forming apart of the hub struc-' Figure 13 is asectional view taken on the line l3l3 of Figure 12; t

Figure 14- is a vertical 'section bly formsa sleeve for the propeller drive shaft; Figure 15is1a similar view to Figure 14 after machiningoperations have been completed; Figure 16 is anend view of the structure shown inFigurel5; I F Figure 17 is a horizontal view through theassembled hub structure} and Figure 18 is a section taken on the linei8--l8 of Figureyl'l. M m As illustrated, the invention will be described: in connection with a propeller hub adapted to receivetwo aligned propeller blades, the pitch of each blade beingcapable of variation simultaneously. Withreference to Figures land the hub structure iscomprised of a maintubular portion}, the opposite ends of which are adaptedto receive propeller blades 4 in any suitable mannerqwhich will enable the. propeller blades to rotate about their longitudinal axesand alsoto; retain the propeller blades securely in placeduring rotation of the hublstructure when a driven by the motor' 6. For example, the blades maybe supported in the hub in-a mannersimi lar to that illustrated and described in-myqco pending application, Serial No; 459,69 L filed september 25, 1942. l r l n i The tubular portion 2 is provided withcircular openings on its forward and rearward surfaces,

which openings are aligned on the rotational axis of the hub structure. In these openings is disposed a tubular member 8 which is welded, to the abutting surfaces of the circular openings so as to constitute an integral part of the hub structure. 1 The tubular member 8, when the device is assembled,is adapted to receive a-propeller drive shaft which is keyed thereto as will be later described.

Spaced outwardly fromthe rotational axisof the hub structure, and disposedtangentially ,with

NT OFFICE Figure 11 is.a similar View to Figure 10 after through a tubular member which after machining and assembase of each propeller blade with a ring gear 20 V respect to the main tubular portion 2 and on opposite sides thereof, are two smaller tubular portions Ill and I2. As shown in Figure 3, these smaller tubular portions l and I2 are rigidly secured to the Wall of the main tubular portion 2 about openings cut in the wall of the tubular portion 2. These smaller tubular portions l0 and I2 themselves are provided with openings which when the smaller tubular portions are secured to the main tubular portion 2, are in registry with the openings in the wall of the main tubular portion 2. The forward ends of. the smaller tubular portions l0 and I2 are closed respectively by capped members [4 and 16 (see Figures 1 and 3) and the tubular member 8 is also closed by a cap member l8 in a similar fashion.

As described in several of my previous applications, such as application Serial No. 459,691,

1 its longitudinal axis and thus causes a change in the pitch of the propeller.

In accordance with the present invention, the

rigidly secured thereto, is housed within an end of the main tubular portion 2 in such a manner that the ring gear 20 extends outwardly into the opening between the main tubular portion 2 and the smaller tubular portion H] (see Figure 3). Here the ring gear 20 is engaged by a worm gear 22 mounted on shaft 24 supported by bearing 26, 26' within a. smaller tubular portion I I] or [2.

The shafts 24 in each of the smaller tubular portions l8 and 12 extend rearwardly from these portions and through closure plugs 21, and their rear ends each have a pinion such as 28, 28 secured thereto. As shown in Figures 1, 2 and 3 these gear pinions 28, 28 are adapted to be engaged by a ring gear 30 driven by an electric or hydraulic motor, or by other means (not shown), controlled by the pilot.

It will be apparent that upon rotation of the ring gear 30 in either direction, the pinions 28, 28' will be rotated, thus turning the worm gears 22 and, through the ring gears 20, rotating the propeller blade roots about their longitudinal axes. This simultaneously changes the pitch of the propeller blades. Obviously, other operative mechanisms for simultaneously engaging and driving the gear pinions 28, 28' may be employed. As an example, reference may be made to my previous application, Serial No. 449,123, filed June 30, 1942.

Figures 4 to 18 inclusive illustrate respectively ing of smaller diameter.

cause the main tubular portion 2 is circular, and these openings 38 and 48 are cut with a cylindri cal cutting tool, the openings will be oval in shape as indicated clearly in Figure 8.

The next step in the operation is the fabrication of the small tubular portions I0 and I2. This step is shown in Figures and 11.. These small tubular portions are formed from steel tub- A cylindrical cutting tool is employed to cut the openings 46 indicated in Figure 11.

, The tubular member 8 (see Figures 1 and 3) is also constructed of a section of tubing, the walls of which are fairly .thick. Such a section of tubing is illustrated in Figure 14. By suitable milling and turning operations, this section of tubing assumes the shape illustrated in Figure from which it will be noted that one end 48 of the tubular member 8 has a greater diameter than the adjacent portion 58. The end 48 has a beveled opening 52 and the end of the portion 50 also-has an enlarged central opening 54. A'small threaded opening i provided in the wall of the 7 ber 8 is provided with splines 58.

the successive steps which may be employed in l, 2 and 3, and which has just been described.

With reference to Figures 4, 5 and 6, the main tubular portion 2 is preferably constructed of a piece of steel tubing or the like. Advantageously the tubing may be made of steel plate bent to form a cylinder with the abutting edges welded. The central opening or cross hole 36 is bored in the main portion 2 and this opening on one side of the tubing 2 is provided with a small notch 38, the purpose of which will be described hereinafter.

The next step in the fabrication of the hub structure is illustrated in Figures '7, 8 and 9. This step comprises cutting or milling openings 38 and 40 on opposite sides of the main tubular portion and spaced equidistantly from the horizontal axis of the main tubular portion 2. I Be- I assembling the variou parts, the tubular member 2 is first heated to expand it sufficiently to permit the tubular member 8 to be inserted through the circular cross openings 36. (See Figures 17 and 13.) disposed so that the knob of the screw 56 is engaged in the notch 38. The outside contacting edges of the tubular portion 2 and tubular member 8 are then brazed or welded such as at 6B." Weld inserts 62 may also be used for strengthening purposes. The knobbed screw in the notch 38 also strengthens the assembly and prevents rotation of tubular portion 2 with respect to tubular member 8 in the event of weakening of the weld lines or shearing of such lines. f

The small tubular members l0 and I2 are now brazed or welded to the main tubular portion 2 as indicated in Figures 12 and 13. Thebrazing or welding is accomplished so that the openings 46' in the small tubular portions register with the openings 40 in the main tubular portion 2. This securing is accomplished preferably by welding.

Screw threads 32 and 34 are then cut in the inner surface of the tubular portion 2 at each end. These screw threads are adapted to receive a socket (not shown) for the propeller blades. Threads are also cut in the front opening 54 of tubular member 8 to receive the closure member l8. The inner surfaces of each end of each of the small tubular members l0 and I2 are then tapped to provide the threads 42 and 44. Finally, the, assembled hub structure is plated such as with operation comprises merely disposing the hub,

structure so that the tubular portion 8 is splined by'keys 5| to a propeller drive shaft (not shown) after which the cap 18 is disposed in the threaded end opening 54. The propeller blade roots are then disposed in opposite ends of the main tubu-. lar member'Z so that the ring gears 20, rigid with the blade roots, are in a position to engage the worm gears 22 which are disposed in the smaller tubular portions l0 and I2 in the manner illustrated in Figure 3. The cap members l4 and It for the front ends of the smaller tubular The tubular member 8 is" members l0 and I2 are then inserted in place and the assembly is thus complete While the hub structure, described is only adapted to support two propeller blades, it is obvious that several of such hub structures may be employed, as for example when two sets of propellers are mounted on coaxial propeller drive shafts so as to drive the setsin contra rotating directions. f l

Obviously changes in form and structure, and

in the method of fabrication and assembly may be made without departing from the inventive concept The inventionis to be limited only to the extent indicated inthe following claims.

I claim:

1. The method of making a hub for variable pitch propellers which comprises first cutting aligned centrally disposed, transverse openings in a cylindrical tubular body, second, milling cutouts of semicircular cross section in said tubular body on opposite sides thereofand tangentially with respect to said body and along lines spaced equidistan-tly from and parallel to the axis of said aligned openings, third, forming a larger tubular member having an enlarged-end and a central cylindrical portion slightly larger than the diameter of such aligned openings in said body, fourth,

heating said body and forcing the larger tubular members abutting respectively a cut-out in. said body thereby forming communicating openings,

between the'interiors of said small tubular mem bers'and the interior of said body. 2 l

2. The method of making a hub for variable pitch propellers which comprises in first, cutting aligned centrally disposed, transverse openings in a cylindrical tubular body; second, milling cut-p outs of semicircular cross section in said tubular body'on opposite sides thereof and tangentially l withrespect to said body and along'lines spaced equidistantly from and parallel to the axis of aligned openings, third, forming a larger tubular member having an enlarged end and a central cylindrical portion slightly largerthan the diameter of said aligned openings in said body,

fourth, heating said body and forcing the larger tubular members through said aligned openings transversely of said tubular body, fifth, joining said tubular body and larger tubular member together after said tubular body is cooled, sixth,

forming a pair of small tubular members with arcua-te cut-outs in one wall thereof, seventh,

cut-out, in said body thereby forming communi- Q eating openings between the interiors of said small tubular members andthe interior of said body, eighth, threading the inner surfaces of said smaller tubular members at each end, and ninth, threading the inner surfaceof said largertubular member at the end opposite said enlarged joining, said small tubular members respectively in said cut-outs of said body with the cut-outs,

of said small members abutting respectively a end. l

ARCHIBALD GRAHAM FORSYTH. 

